RE: SCIENCE AND CLASSIFICATION

["Ken Kinman" <kinman@hotmail.com>]

Dear All,
      First of all, I would very strongly recommend that all systematists 
read the 1998 paper by Eric B. Knox (Biological Journal of the Linnean 
Society, 63:1-49; entitled "The use of hierarchies as organizational models 
in systematics").  It's one of those rare "stand-out" papers that 
occasionally punctuate the systematics literature every decade or so, but 
not always fully appreciated in the years just after publication.
      Anyway, I have been watching the bird-dinosaur debate for many, many 
years, and have immersed myself more deeply into it for the past couple of 
years.  Even among the vast majority, who now agree that birds are dinosaur 
descendants, there have already been endless debates over whether 
mononykines are birds, or if Rahonavis is a bird, or Caudipteryx, 
Protarchaeopteryx, Bambiraptor, Unenlagia ("half-bird"), Microraptor, 
oviraptors, and so on (and then there's the Protoavis mess which is a story 
unto itself).
     My contention is that much of this confusion and needless wrangling is 
no longer due to the lack of information, but rather due to the use of 
Archaeopteryx as the basalmost bird (the cladistic definition I have 
accepted, up to now, for the sake of stability in the short-term).  But we 
now have sufficient data to define Aves in a more scientifically rigorous 
fashion (osteologically), just as was done with Mammalia decades ago.  The 
presence of hair and lactation roughly corresponds to the scientific 
definition, so there have been no big problems reconciling the two 
(communication went smoothly, at least until cladistic splintering muddled 
it up with Mammaliamorpha and the like).
      The new definition of Aves, if done correctly, will do for birds what 
has so long been successfully done with mammals. The scientific definition 
will be precise (osteological), but it will roughly coincide with the 
presence of "vaned" feathers.  All those more primitive "protofeathers" on 
Sinosauropteryx, the newly-discovered pterosaur, and even that 
bristly-tailed psittacosaur, are apparently just that (PROTOfeather 
homologs).  Whether the structures of Beipiaosaurus are best regarded as 
advanced protofeathers or primitive vaned feathers remains to be seen.  In 
any case, a precise osteological definition should take precedence over 
feathers, eggshells, origins of flight, and other characters that fossilize 
poorly (and that obviously includes bird excrement as well).  :-)
     Within this new context, the evolution of brooding and powered flight, 
the ornithoid eggshell evidence, and so on, will begin to make more sense, 
and it will also clarify many of the debates that have paleontologists and 
ornithologists insulting each other in the press and in other public forums 
(fora?).  The whole Longisquama debate is one of the more embarrassing 
examples.
      I am proposing a long-thought-out, moderate paradigm shift that I 
believe will enhance stability.  Both scientists and the public alike will 
have to learn that the old "bird = feather possession" idea is inaccurate 
and out-of-date.  But shifting to the possession of "vaned" feathers seems 
the best way to accomplish a smooth transition (especially with the public). 
 What we now have is confusion and taxonomic instability.  The question in 
my mind is not *whether* we should draw a new line, but *where* it should be 
drawn.  To continue drawing the line at Archaeopteryx (eclectically or 
cladistically) is a tradition that I think we must abandon for everyone's 
sake.
      More generally, we are faced with a decision between: (1) an eclectic 
emphasis on apomorphy (character)-based taxa or (2) a purely cladistic 
emphasis on node- and stem-based taxa.  The latter seems to sacrifice 
stability of content in favor of stability of definition (definitions which 
cladists are already fighting over, requiring a new bureaucratic code to 
settle them, and no sign that its decisions will be widely followed anyway).
       If you look at it from a broad perspective, all classifications are 
arbitrary and "typological" to some degree, and pure cladism is just 
promoting a new form of arbitrary "typology".  Benton (2000) has already 
pointed out that in the end, we will be no better off, and thatin many ways 
we will be much worse off if we follow this path.  The pendulum has swung 
too far already (swinging so far, that even I have been ousted from the 
"Cladists Club", which is very odd because some eclecticists think I'm too 
much of a "cladist").
     Anyway, I certainly look forward to Mickey Mortimer's upcoming 
analysis.  And I will seriously consider it's outcome as I continue 
searching for a precise osteological definition of Aves that can be made 
more precise in the future (as has been done with the Mammalia definition).
         ------  Cheers, Ken Kinman



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